Bioreduction of mobile uranyl(VI) (UO2 ) to sparingly soluble uraninite (U(IV)O2(s)) is a strategy that has been proposed for in situ remediation of uranium contaminated aquifers. That strategy faces the challenge of reoxidation of uraninite, with consequent release of soluble uranyl when the stimulation of U(VI) bioreduction is terminated. We tested the effects of supplemental organic carbon (...

The thermophysical performance and solid mechanics behavior of UO2-36.4vol % BeO fuel pellets cladded with Zircaloy, SiC, and FeCrAl, and Zircaloy cladding materials coated with SiC and FeCrAl, are investigated based on simulation results obtained by the CAMPUS code. In addition, the effect of coating thickness (0.5, 1 and 1.5 mm) on fuel performance and mechanical interaction is discussed. The...

T na m What Is Depleted Uranium? Depleted uranium is created as a byproduct during the processing of natural uranium to make it suitable for use as fuel in nuclear power plants or as a component in nuclear weapons. In natural uranium, 99.27% of the mass consists of atoms of uranium-238. About 0.72% of the mass consists of atoms of uranium-235, and a very small amount (0.0055% by mass) is uraniu...

Silica, or silicon dioxide (SiO2), is a group IV metal oxide, which naturally occurs in both crystalline and amorphous forms (i.e. polymorphic; NTP, 2005). The various forms of crystalline silica are: α-quartz, β-quartz, α-tridymite, β-tridymite, α-cristobalite, β-cristobalite, keatite, coesite, stishovite, and moganite (NIOSH, 2002). The most abundant form of silica is α-quartz, and the term q...

Despite the current interest in selenium chemistry [1—6], oxidations by selenium dioxide remained limited to only a few classes of compounds, mainly alkenes and carbonyl compounds, in addition to some special cases [7, 8]. Selenium dioxide is the cheapest and most convenient selenium reagent, and an extension of its applications to other types of com­ pounds is therefore of considerable interes...

In the present work the methods of relativistic quantum chemistry have been applied to a number of small systems containing heavy elements, for which relativistic e ects are important. First, a thorough introduction of the methods used is presented. This includes some of the general methods of computational chemistry and a special section dealing with how to include the e ects of relativity in ...

abstract   background : natural uranium exists in earth crust and seawater. the concentration of uranium might increase by human manipulation or geological changes. the aim of this study was to verify susceptibility of laser flourimetry method to determine the uranium concentration in caspian sea and persian gulf water.   materials and methods : laser flourimetric method was used to determine t...